https://bugs.freedesktop.org/show_bug.cgi?id=98988
--- Comment #2 from John Brooks bugs.freedesktop@fastquake.com --- Commenting out http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/...
or removing /lib/firmware/radeon/bonaire_uvd.bin fixes the problem on my system.